Heat dissipation device

ABSTRACT

A heat dissipation device includes a first board body and a second board body. The first board body has a first face and a second face. The second face is formed with a rough structure. The second board body has a third face and a fourth face. The fourth face is mated with the second face and covered by the second face. The second and fourth faces together define a chamber. A working fluid is filled in the chamber. The rough structure is coated with a coating. By means of the rough structure and the coating, the cost for the heat dissipation device is reduced and the thermal resistance of the heat dissipation device is lowered.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a heat dissipation device, and more particularly to a heat dissipation device, which is manufactured at lower cost and has greatly lowered thermal resistance.

2. Description of the Related Art

Along with the rapid advance of scientific and technologic industries, electronic devices have more and more powerful functions. For example, the operation speed of central processing unit (CPU), chip set and electronic components of display unit has become faster and faster. This leads to higher heat generated by the electronic components per unit time. In case that the heat is not dissipated in time, the operation of the entire electronic device will be affected or even the electronic components will burn out.

In general, the heat generated by the electronic components is dissipated by means of cooling fan, heat sink or heat pipe. The heat sink is in contact with a heat source. Via the heat pipe, the heat generated by the heat source is transferred to a remote end for dissipating the heat. Alternatively, the cooling fan can forcedly guide airflow to carry away the heat of the heat sink. With respect to a narrow space or a large-area heat source, a vapor chamber is often selectively used as a heat conduction member for dissipating the heat.

A conventional vapor chamber is composed of two board materials mated with each other. The mating faces of the board materials are formed with capillary structures (such as channeled structures, mesh structures or sintered bodies or a combination thereof). The board materials are mated with each other to define a closed chamber in a vacuum state. A working fluid is filled in the chamber. In order to increase the capillary limit, the board materials are supported by coated copper pillars, sintered pillars or foamed pillars as backflow passages. When the liquid working fluid in the evaporation section of the vapor chamber is heated, the liquid working fluid is evaporated into vapor phase. After the vapor working fluid flows to the condensation section of the vapor chamber, the vapor working fluid is condensed into liquid phase. The liquid working fluid then flows back to the evaporation section through the copper pillars. Accordingly, the working fluid is circularly used. After the vapor working fluid in the condensation section is condensed into liquid working fluid in the form of small water beads, due to gravity or capillary attraction, the working fluid can flow back to the evaporation section.

However, in the conventional vapor chamber, the backflow speed of the working fluid is too slow. This often leads to vacant combustion or poor thermal homogeneity. As a result, the working fluid can be hardly effectively transformed between liquid phase and vapor phase for heat exchange. In design, the capillary attraction of the capillary structure to the liquid working fluid can be increased to speed the backflow of the liquid working fluid. In this case, the heat transfer performance of the vapor chamber can be effectively enhanced. However, conventionally, the capillary attraction and the fluid resistance are two design factors conflicting with each other. In consideration of increase of the capillary attraction, it is necessary to provide a capillary structure with smaller voids. However, the smaller voids will apply greater resistance against the fluid to hinder the working fluid from flowing back to the evaporation section.

Reversely, in the case that it is considered to reduce the fluid resistance, it is necessary to provide a capillary structure with larger voids to facilitate backflow of the working fluid. However, under such circumstance, the capillary attraction will be decreased.

To overcome the above problem, a vapor chamber with complex micro-structures is now available in the market. Such vapor chamber includes a first capillary structure layer and a second capillary structure layer. The first and second capillary structure layers have different sizes of voids. However, the manufacturing processes of both the conventional single-layer vapor chamber and the complex vapor chamber are complicated and it is hard to thin the vapor chambers. Moreover, it is hard to control the quality of the vapor chambers. As a result, the cost is higher and the ratio of defective products is increased.

According to the above, the conventional vapor chamber has the following shortcomings:

1. The cost is higher.

2. The thermal homogeneity is poorer.

3. The conventional vapor chamber has a considerable thickness.

4. The thermal resistance of the conventional vapor chamber is higher.

SUMMARY OF THE INVENTION

It is therefore a primary object of the present invention to provide a heat dissipation device, which is manufactured at greatly lowered cost.

It is a further object of the present invention to provide the above heat dissipation device, which has lower thermal resistance.

It is still a further object of the present invention to provide the above heat dissipation device, in which the condensation section has better thermal homogeneity.

To achieve the above and other objects, the heat dissipation device of the present invention includes a first board body and a second board body. The first board body has a first face and a second face. The second face is formed with (or provided with) a rough structure. The second board body has a third face and a fourth face. The fourth face of the second board body is mated with the second face of the first board body and covered by the second face. The second and fourth faces together define a chamber. A working fluid is filled in the chamber. The rough structure of the second face or the fourth face is coated with a coating. Alternatively, both the rough structure of the second face and the fourth face are coated with coatings.

In the above heat dissipation device, the second face is partially or totally formed with the rough structure and the coating coated on the rough structure is a dioxide silicon coating. Also, the coating is a hydrophilic coating or a hydrophobic coating. When the third face of the second board body absorbs heat, the liquid working fluid is heated and evaporated into vapor working fluid. Then, the vapor working fluid on the second face of the first board body is condensed into liquid working fluid. By means of the rough structure, the liquid working fluid is quickly pulled to a section of the second face corresponding to the position of the heat source. The collected liquid working fluid then flows back to the fourth face of the second board body. Accordingly, the rough structure can speed the backflow of the liquid working fluid and lower the thermal resistance of the heat dissipation device as well as enhance the thermal homogeneity thereof. Also, the rough structure overcomes the problems of the conventional vapor chamber that the manufacturing process is complicated and the quality is hard to control. Therefore, the ratio of defective products is greatly reduced and the manufacturing cost is greatly lowered.

BRIEF DESCRIPTION OF THE DRAWINGS

The structure and the technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings, wherein:

FIG. 1A is a perspective exploded view of a first embodiment of the present invention;

FIG. 1B is a perspective assembled view of the first embodiment of the present invention;

FIG. 1C is a sectional view of the first embodiment of the present invention;

FIG. 1D is an enlarged view of circled area of FIG. 1C;

FIG. 1E is a sectional view of the first embodiment of the present invention in another aspect;

FIG. 1F is an enlarged view of circled area of FIG. 1E;

FIG. 2A is a sectional view of a second embodiment of the present invention;

FIG. 2B is an enlarged view of circled area of FIG. 2A;

FIG. 3A is a sectional view of a third embodiment of the present invention;

FIG. 3B is an enlarged view of circled area of FIG. 3A;

FIG. 4A is a sectional view of a fourth embodiment of the present invention;

FIG. 4B is an enlarged view of circled area of FIG. 4A;

FIG. 5A is a sectional view of a fifth embodiment of the present invention;

FIG. 5B is an enlarged view of circled area of FIG. 5A;

FIG. 6 is a perspective exploded view of a sixth embodiment of the present invention; and

FIG. 7 is a perspective exploded view of a seventh embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Please refer to FIGS. 1A, 1B, 1C, 1D, 1E and 1F. FIG. 1A is a perspective exploded view of a first embodiment of the present invention. FIG. 1B is a perspective assembled view of the first embodiment of the present invention. FIG. 1C is a sectional view of the first embodiment of the present invention. FIG. 1D is an enlarged view of circled area of FIG. 1C. FIG. 1E is a sectional view of the first embodiment of the present invention in another aspect. FIG. 1F is an enlarged view of circled area of FIG. 1E. According to the first embodiment, the heat dissipation device of the present invention includes a first board body 10 and a second board body 11. The first board body 10 has a first face 101 and a second face 102 (condensation section). The second face 102 is partially (FIGS. 1C and 1D) or totally (FIGS. 1E and 1F) formed with (or provided with) a rough structure 1021. In the case that the second face 102 is partially formed with the rough structure 1021, the rough structure 1021 is positioned right above a heat source 2 (CPU, transistor or other heat generation object (component)). The rough structure 1021 of the second face 102 is coated with a coating 1022 of dioxide silicon.

In this embodiment, preferably, the rough structure 1021 of the second face 102 is a capillary structure with micro-channels. The capillary structure is formed by means of mechanical processing (stamping, marking or sculpturing) or etching. The rough structure 1021 is a recessed/raised structure. The coating 1022 is a hydrophilic coating or a hydrophobic coating. In this embodiment, the coating 1022 is, but not limited to, a hydrophilic coating.

The second board body 11 has a third face 111 and a fourth face 112 (evaporation section). The fourth face 112 of the second board body 11 is mated with the second face 102 of the first board body 10 and covered by the second face 102. The second and fourth faces 102, 112 together define a chamber 113. The third face 111 is in contact with the heat source 2.

A working fluid 12 is filled in the chamber 113. The working fluid 12 is selected from a group consisting of pure water, methanol, acetone, coolant and ammonia.

According to the above arrangement, the second face 102 is partially or totally formed with the rough structure 1021 coated with a hydrophilic or hydrophobic coating 1022. When the third face 111 of the second board body 11 in contact with the heat source 2 absorbs heat, the liquid working fluid 12 is heated and transformed into vapor working fluid 12. Then, the vapor working fluid 12 on the second face 102 of the first board body 10 is condensed into liquid working fluid 12. By means of the rough structure 1021, the liquid working fluid 12 is quickly collectively pulled to a section (the hottest part of the condensation section) of the second face 102 corresponding to the position of the heat source 2. The collected liquid working fluid 2 then flows back to the fourth face 112 of the second board body 11. Accordingly, the rough structure 1021 can speed the backflow of the liquid working fluid 2 and lower the thermal resistance of the heat dissipation device 1 as well as enhance the thermal homogeneity. Also, the rough structure 1021 overcomes the problems of the conventional vapor chamber that the manufacturing process is complicated and the quality is hard to control. Therefore, the ratio of defective products is greatly reduced and the manufacturing cost is greatly lowered.

Please now refer to FIGS. 2A and 2B. FIG. 2A is a sectional view of a second embodiment of the present invention. FIG. 2B is an enlarged view of circled area of FIG. 2A. The second embodiment is partially identical to the first embodiment in component and relationship between the components and thus will not be repeatedly described hereinafter. The second embodiment is mainly different from the first embodiment in that the rough structure 1021 has a waved form. The rough structure 1021 is coated with a coating 1022. The rough structure 1021 can speed the backflow of the liquid working fluid and enhance the thermal homogeneity as well as lower the thermal resistance of the heat dissipation device and lower the manufacturing cost.

Please now refer to FIGS. 3A and 3B. FIG. 3A is a sectional view of a third embodiment of the present invention. FIG. 3B is an enlarged view of circled area of FIG. 3A. The third embodiment is partially identical to the first embodiment in component and relationship between the components and thus will not be repeatedly described hereinafter. The third embodiment is mainly different from the first embodiment in that the rough structure 1021 has a saw-toothed form. The rough structure 1021 is coated with a coating 1022. The rough structure 1021 can speed the backflow of the liquid working fluid and enhance the thermal homogeneity as well as lower the thermal resistance of the heat dissipation device and lower the manufacturing cost.

Please now refer to FIGS. 4A and 4B. FIG. 4A is a sectional view of a fourth embodiment of the present invention. FIG. 4B is an enlarged view of circled area of FIG. 4A. The fourth embodiment is partially identical to the first embodiment in component and relationship between the components and thus will not be repeatedly described hereinafter. The second embodiment is mainly different from the first embodiment in that the coating 1022 is coated on the fourth face 112 (evaporation section).

Please now refer to FIGS. 5A and 5B. FIG. 5A is a sectional view of a fifth embodiment of the present invention. FIG. 5B is an enlarged view of circled area of FIG. 5A. The fifth embodiment is partially identical to the first embodiment in component and relationship between the components and thus will not be repeatedly described hereinafter. The fifth embodiment is mainly different from the first embodiment in that both the rough structure 1021 of the second face 102 and the fourth face 112 are coated with the coatings 1022. This also can speed the backflow of the liquid working fluid and enhance the thermal homogeneity as well as lower the thermal resistance of the heat dissipation device and lower the manufacturing cost.

Please now refer to FIG. 6, which is a perspective exploded view of a sixth embodiment of the present invention. The sixth embodiment is partially identical to the first embodiment in component and relationship between the components and thus will not be repeatedly described hereinafter. The sixth embodiment is mainly different from the first embodiment in that the second board body 11 has a capillary structure 1121 formed on the fourth face 112. The capillary structure 1121 is selected from a group consisting of channeled structure, sintered powder body and mesh body. In this embodiment, the capillary structure 1121 is, but not limited to, a sintered powder body for illustration purposes only.

Please now refer to FIG. 7, which is a perspective exploded view of a seventh embodiment of the present invention. The seventh embodiment is partially identical to the first embodiment in component and relationship between the components and thus will not be repeatedly described hereinafter. Also referring to FIG. 1E, the seventh embodiment is mainly different from the first embodiment in that at least one support pillar 1131 is disposed in the chamber 113. Two ends of the support pillar 1131 are respectively connected to the second face 102 (condensation section) and the fourth face 112 (evaporation section). In addition, a capillary structure 1131 a is disposed on an outer surface of the support pillar 1131. The capillary structure 1131 a is selected from a group consisting of channeled structure, sintered powder body and mesh body. In this embodiment, the capillary structure 1131 a is, but not limited to, a sintered powder body for illustration purposes only.

The rough structure 1021 (not shown) is tapered in height from the center of the board body to the edges of the board body.

According to the above embodiment, when the third face 111 of the second board body 11 absorbs heat, the liquid working fluid 12 is heated and transformed into vapor working fluid 12. Then, the vapor working fluid 12 on the second face 102 of the first board body 10 is condensed into liquid working fluid 12. Thanks to the hydrophilicity of the coating 1022 and by means of the capillary attraction of the capillary structure 1131 a of the support pillar 1131, the liquid working fluid 12 is pulled from the condensation section back to the evaporation section. Accordingly, the backflow of the liquid working fluid is speeded and the thermal homogeneity is enhanced. Also, the thermal resistance of the heat dissipation device 1 is lowered.

In conclusion, in comparison with the conventional vapor chamber, the present invention has the following advantages:

1. The cost is lowered.

2. The thermal homogeneity of the heat dissipation device is enhanced.

3. The thermal resistance of the heat dissipation device is lowered.

The present invention has been described with the above embodiments thereof and it is understood that many changes and modifications in the above embodiments can be carried out without departing from the scope and the spirit of the invention that is intended to be limited only by the appended claims. 

What is claimed is:
 1. A heat dissipation device comprising: a first board body having a first face and a second face, the second face being formed with a rough structure; and a second board body having a third face and a fourth face, the fourth face of the second board body being mated with the second face of the first board body and covered by the second face, the second and fourth faces together defining a chamber, a working fluid being filled in the chamber.
 2. The heat dissipation device as claimed in claim 1, wherein a heat source is attached to the third face.
 3. The heat dissipation device as claimed in claim 2, wherein the rough structure of the second face or the fourth face is coated with a coating.
 4. The heat dissipation device as claimed in claim 3, wherein both the rough structure of the second face and the fourth face are coated with coatings.
 5. The heat dissipation device as claimed in claim 4, wherein the second face is partially or totally formed with the rough structure.
 6. The heat dissipation device as claimed in claim 5, wherein the second face is partially formed with the rough structure and the rough structure is positioned right above the heat source.
 7. The heat dissipation device as claimed in claim 3, wherein the coating is a hydrophilic coating or a hydrophobic coating.
 8. The heat dissipation device as claimed in claim 1, wherein the working fluid is selected from a group consisting of pure water, methanol, acetone, coolant and ammonia.
 9. The heat dissipation device as claimed in claim 6, wherein the rough structure of the second face is a capillary structure with micro-channels, the capillary structure being formed by means of mechanical processing or etching.
 10. The heat dissipation device as claimed in claim 9, wherein the mechanical processing is stamping, marking or sculpturing.
 11. The heat dissipation device as claimed in claim 1, wherein the rough structure has a recessed/raised form, a waved form or a saw-toothed form.
 12. The heat dissipation device as claimed in claim 1, wherein the second board body has a capillary structure formed on the fourth face.
 13. The heat dissipation device as claimed in claim 12, wherein the capillary structure is selected from a group consisting of channeled structure, sintered powder body and mesh body.
 14. The heat dissipation device as claimed in claim 1, wherein at least one support pillar is disposed in the chamber, two ends of the support pillar being respectively connected to the second face and the fourth face, a capillary structure being disposed on an outer surface of the support pillar.
 15. The heat dissipation device as claimed in claim 14, wherein the capillary structure is selected from a group consisting of channeled structure, sintered powder body and mesh body.
 16. The heat dissipation device as claimed in claim 3, wherein the coating is a dioxide silicon coating. 